Electric sign system



J. R. ANDERSEN 2,123,459

ELECTRIC SIGN` SYSTEM Filed April 17, 1936 mmmmbmwh flash Off Voltage 31a/vanto@ `Patented July l2, `1938` UNITED STATES PATENT OFFICE a claims.

This invention relates generally to electric signs; and more particularly to signs Where letters for pictorial representations of objects, are formed on a display bank of electric lamps, and

are caused to change position intermittently on the bank with such vfrequency as to give the impression that the letters or representations are in continuous movement from one end of the display bank to the other. Preferably, the invention` utilizes neon or similar gas tubes for the production of the traveling letters or pictorial representations, the energization of these tubes being controlled by the movement of a sheet or ribbon of material perforated or otherwise w marked to correspond with the letters or pictorial representation to be reproduced in the display bank.

'I'he main object of the invention is to eliminate the contacty boards, relays and similar devices heretofore Afound necessary ior the operation' of this type of changeable sign.

Another object of the invention is to provide a display system in which all contact making and breaking points are eliminated, and in which the wiring is substantially decreased over any' thing ofthis character heretofore in use.

A further object of the invention is to simplify the design of devices of this character so that the cost of installation and maintenance of dea@ vices of this general type may be greatly reduced.

Other objects of the invention will become apparent as the detailed description thereof proceeds.

In the drawing: p

w Figure 1 is a diagrammatic lay-out of a bank of lamps constituting the sign proper; and the mechanism for controlling these lamps to form the moving letters or pictorial representations.

Figure 2'is an enlarged wiring diagram illusm trating the principle of operation involved in the control of the lamps; and e Figure 3. illustrates graphically the voltage .changes in a direct current supply, which effects the successive lighting of the lamps in the w rows in the sign.

It is 4generally known that luminous gas tubes of the neon lamp type require a. certain voltage between the electrodes before ionization and glowcan be secured.v This certain voltage for 50 convenience `will be termed the flash-on" `voltage. Once ionization has started, the voltage may be lowered appreciably before ionization and glow ceases. It will be convenient to consider the Voltage at which ionization ceases as the flash- 55 od voltage. The voltage difference between (ci. 1v1-35o) flash-ori and flash-off ranges up to about volts. The voltagenecessary to maintain ionization or glow is from five to six volts less than the flash-on" voltage. The D. C. current supply 5 may be regulated to provide this lower voltage substantially constant. Now lamps of this type cannot start ionization directly from this constant voltage; but must have some additional voltage applied thereto to provide additionalv ve 10 or six volts required to start ionization. In the present invention, this additional voltage is provided by periodically interrupting the D. C. current, and interposing in the circuit thereof,

a transformer for each lamp, which transformer, i5 at each interruption, raises the voltage of the flash-on point necessary to set up ionization of the lamp connected thereto.

Each lamp is provided with a transformer; and the transformers of each row are connected so that the circuit of each lamp includes the primary of one transformer and the vsecondary of another transformer. Preferably, the ratio of the windingsin each transformer is 1:5, the primary having the lower number of turns. 25

In the drawing the sign is designated generally by the reference numeral l. As shown in the drawing, there are eight horizontal rows of lamps in the sign. It will be understood that the number of horizontal rows and the number of lamps 3 in each row, will depend upon the `desired detail in the picture to be formed on thel sign.

The lighting of the lamps is controlled by a strip t of transparent sheet material mounted on rollers t and i for movement through a light box 5 in which is mounted, below the plane of movement of said strip, a series of light sensitive cells 6, only one of which is shown in Figure 2 of the drawing. .'I'he`strip2 is marked in l accordance with the letter or other representation to be shown by illumination of lamps on the sign i. For example, the letter L outlined by opaque circular areas on the strip 2 is reproduced by illumination of correspondingly arranged lamps on the sign I.

Direct current for energizing the lamps is supplied by the mains 'i and 8. The positive main l is connected to a wire 9 which extends across the bank of lamps in the sign i. A positive feed wire i@ extends between the two horizontal'rows 5 A and B of the lamps, and is connected to alternate transformers in the row A, For example, the positive wire I0 is connected to the transformers T-I, T-3, 'IL-5, etc. in row A. The return wire ii for the wire I0 and connected 55 transformers and lamps is connected to the transformers T-2, T-4, T-6, etc.; and this wire II is connected by wire I2 to the negative main 4.

The wire I also supplies positive current in the same order to the transformers and lamps in the row B of the sign, the wire I2 being the the positive feed for rows C and D, while wire I4 is the return for rows D and E; and so on down all of the rows of lamps and transformers in the sign. This arrangement obviously 'effects an enormous saving in wiring, in comparison with those systems wherein each row of lamps is provided with positive and negative wires connected to the mains independently of the positive and negative wires in the other rows.

As shown in the drawing, a motor N rotates the shaft I5 by means of the gears I6 and I1, to operate theinterrupter CB and the strip roller 3. Wires I8 and I9 connect the interrupter CB to the return main 8, the rate -of interruption being timed with the movement of the strip 2.

The strip 2 passes through the light box 5, and its unperforated parts obstruct the passage of light from a lamp 20 to a bank of light sensitive circuit controllers arranged within the box on the side of the strip opposite to the lamp 20. The number of circuit controllers corresponds to the number of horizontal rows of lamps in the sign I; and only 'one is required to control the lighting of the lamps in each row. For example, the circuit closer 6 of Figures l 'and 2 controls the starting of the ionization in row A of the lamps in the sign I. A description of this particular control will sufiice to explain the operation of all the others, since all are operated in the same manner.

A transformer 2I is coupled to the return main 8. The secondary of this transformer 2i is connected at one end by wire 22 to one terminal of the circuit controller 6. A wire 23 connects the other end of the secondary of transformer 2I through the secondary 24 of a. transformer 25 to the other terminal of the circuit controller 6. A balanced resistance R, with the same resistance as the light sensitive circuit closer when under illumination through strip 2, is interposed, with a winding 26 similar to secondary 24, as a bypass for the transformer 2I. The necessity of the balancing resistance R, and the winding 28 as a bypass, is based on the assumption that a transparent tape with opaque letters is used. The value of the resistance R is of the same value as that of the photo-electric cell 6 when this is under illumination through the transparent tape. The winding 26 is in inductive relation to winding 24. It has the same number of -turns `as winding 24, but` is so connected that its flux Y counteracts that of winding 24. When an impulse is started from transformei 2l, and no opaque letters on the tape are opposite the photoelectric cell, we get the same amount of current in winding 26 and 24. These currents will neutralize each other, thus preventing any current from flowing in winding 21.

If, however, there is an opaque area in front of the photo-electric cell 6, the resistance of this will increase due to absence of light, thus decreasing the current flow in winding 24. Therefore, the current in winding 26 will be transmitted to winding 21, thus causing the lamp L-I to light up.

The primary 21 of transformer 25 is connected at one end by wire 2B to the positive wire 9 which is connected to the center of the transformer T-I in row A of the lamp bank. The other end of. primary 21 is connected by wire 29 to the primary of the transformer T-I.

In connection with the operation of the sign it will be convenient to consider the' operation of the lamps and transformers in row A; and,v in this connection consider the operation of the'device under the control of the yopaque representation of'the letter L" on the strip 2 as it moves from right to left as shown in Fig. 1 of the drawing. As shown in this figure. the letter L" has its opaque areas spaced apart transversely of the strip 2 to correspond with the transverse spacings of the lamps in the sign I. Let it be assumed now that the letter L on the strip approaches the light box 5 from the right hand side thereot As soon as the vertical leg of the letter L overlies the bank of circuit controllers 6, all the lamps in the first transverse row of the sign begin to glow. The circuit for the top circuit closer and lamp row A of the sign is illustrated in Figure 2. It will be apparent from the drawing that interrupted direct current flows from the mains 1 and 8 through all the lamps in the sign, but its voltage being below the flash-on value is insuflicient to start ionization. Each letter of the sign is composed of a number of single lamps. These lamps are arranged in horizontal and vertical rows. It takes 5 vertical rows to make one letter like H to L. As one interruption will transmit one vertical row five interruptions are needed to transmit each letter, and the speed of the tape is adjusted accordingly.

When the circuit closes through the top circuit closer 6, the transformer 25 through the primary of lamp transformer T-I adds its irn-v pulse to the interrupted current from the mains 1 and 8. This increases the voltage to the ilashon point and lamp L-I begins to glow. As the strip 2 moves to the left, the opaque areas of the letter Lmove away from the circuit controller 6, and the circuit which includes it becomes broken. However, the interruptions in the current are timed so that the rise in vol/tage in the transformer T--2 added to the steady voltage through the mains "I and 8 sets up ionization of the lamp L-2. The other lamps, in the same transverse row are similarly energized, so that all in that row glow notwithstanding the factY that the vertical leg of the letter L on the strip 2 is no longer over the row of circuit closers 6. In this manner all the transverse rows of lamps in the sign become ionized in succession, and give the effect of movement of the letter from one end of the sign to the other.

In an actual installation of this device, it was found that the voltage loss through the primary winding was approximately two volts when the lamps were glowing. When. lamp was turned o by interruption in the-current, it was found that a voltage of nearly ten volts would be in duced in the secondary winding of the transformer. This secondary winding is so connected that when the lamp in series with the primary winding was turned on the direction of the current in the secondary winding was opposed to the l interrupted D. C. in the circuit. In this condition no ionization could :take place in the next lamp at that time. However, when the first lamp flashes oil, the impulse in the second is added to that of -the interrupted D. C. to produce a total voltage mary and secondary windings, the secondary impulse does not appear before the interrupted dif rect current has been restored to full strength.

The ratio of 1:5 in the transformers eliminates all possibility of reversal of impulses. In the secondarywindings the voltage loss should be made as small as possible.

In Figure 1 .of the drawing, the transformer circuits to lthe different `light sensitive circuit closers are merely indicated in diagram. It will be understood, however, that hook-up for each circuit closer is substantially the same as that shown in Figure 2. It is not essential that the control strip 2 be transparent and have the letters formed thereon by opaque areas. It is contemplated that the same 'result may be secured by using opaque strip with transparent letters formed thereon. The character of theistrip would depend upon the construction of the light sensitive circuit closers which may be of any well-known type. However, the circuit .shown in the drawing is designed for use with a transparent strip having opaque letters thereon. The resistance of the photo-electric cell increases with decreasing light. When the cell is illuminated through the transparent strip, the impulses through the windings 26 and 24 counterbalance each other. When the opaque area appears the circuit through the cell is broken and the impulse through the winding 26 actually transmits that impulse to winding 21.

It is to be understood that the invention is not to be considered as limited to the specific construction and arrangement described herein, lsince it -is evident that many changes may be; made without departing from the scope oi the invention as defined by the claims'appended hereto.

What I claim is:

1. In an electric sign system, a row oi' glow 4 discharge lamps having the characteristics that blocking the passage of light .tonner primary of the preceding lamp connec` tions and a transformer primaryassociated with a. transformer secondary of a succeeding lamp, the relation of the voltage of the secondaries included in the connections to the lamps with respect to the voltage-applied to the lamps being such that the voltage induced in the secondary of its transformer by the transformer primary ythey maintain' discharge at a lower voltage than will oppose the voltage of the source when current in the primaryis established and aid the voltage of the source when current in the primary is interrupted, the connections of the rst lamp inthe row including the primary of a transformer for the secondary of the succeeding lamp, means for periodically interrupting the supply of current from said source to all oi said lamp connections for a period suiiicient to extinguish any lamp which is in4 discharge condition and for again kestablishing said supply of current while the voltage is still present in the secondary included in a lamp connection due to the interruption of the discharge, if any, in the preceding lamp connection and means operating in time relation to said interrupting means for determining `after eachiinterruption whether the rst lamp in the row should be discharged or not after the current from said source to the connections'is yreestablished.

2. The apparatus set forth in claim 1 in which the last` named means comprises a light sensitive circuit controller, a source of light for energizing said controller, and means movable between said source and controller for blocking the' passage of light to said controller.4

3. The apparatus set forth in claim 1 in which the last named means includes: a light sensitive circuit controller, a source of light for energizing said controller, and an endless transparent sheet -of material movable between said source of light and said controller and provided with means for rays from said source to said controller. i

J OHANRIBERG ANDERSEN. 

